The lens will have a different type of stabilization (VC) than the previous version which will bring the size down. Tamron actually claims that this 70-200mm will be the smallest in its class. (via Tamron 70-200mm F2.8 Lens Coming Soon)

The lens will have a different type of stabilization (VC) than the previous version which will bring the size down. Tamron actually claims that this 70-200mm will be the smallest in its class. (via Tamron 70-200mm F2.8 Lens Coming Soon)

Source: thephoblographer.com